Ristocetin and other antibiotics in its class interfere with the biosynthesis of bacterial cell wall by complexation with peptide intermediates. This project involves an attempt to develop an understanding of the binding process on a molecular level. As the first phase of this study, the structures of ristocetin A and a closely related antibiotic, ristoymcin A, are being determined. The peptide constituents of both antibiotics are now established and efforts this year will be devoted to the peptide sequence and to the carbohydrate portions of both compounds. Similar studies will also be undertaken with the actinoidins, although not all of the peptide constituents have been identified yet.